This invention relates to assembly techniques for storage systems. More particularly, the invention relates to a welding process for the assembly of disk cartridges.
Disk based data storage devices for storing digital electronic information have been in use in the computer industry for several decades. The storage devices operate by storing digital information on magnetic disk media, which can be either rigid or flexible and are mounted on a rotating hub. These storage devices are commonly referred to as disk drives. Disk drives come in two varieties: removable media and fixed media drives.
Removable media drives accept the disk media in the form of a removable disk cartridge. When the disk cartridge is inserted into a disk drive, a spindle motor in the drive couples with the disk hub in order to rotate the disk within the cartridge at a given speed. In fixed media drives, by contrast, the disk hub is permanently attached to the spindle motor. Disk drives typically employ either a linear actuator mechanism or a rotary actuator mechanism. The actuator positions the read/write head(s) of the disk drive on the recording surface(s) of the disk.
The general technological trend is one of shrinking component sizes. This trend also applies to the disk drive industry. For example, 2" inch disk drives (and smaller) are becoming prevalent. Correspondingly, disk cartridges, and the tolerances required in manufacturing them, are shrinking as well. In such disk cartridges, the relative placement of components becomes a key technical issue. For example, to ensure proper operation of the disk cartridge, as well as to ensure portability of the disk cartridge from one disk drive to another, the spatial dimensions of the cartridge, such as its thickness, must be controlled precisely. Traditionally, disk cartridge components were assembled by screwing or gluing components together. However, where the coplanarity and dimensional relationship of the components is critical, this traditional method provides insufficient precision. Additionally, the screws or glue used to assemble the components takes up space in the cartridge. As cartridges become smaller, less space in the cartridge can be budgeted for the assembling mechanisms.
Traditional welding techniques of metal components use lap joints or butt joint of metallic components. However, where the dimensional tolerances are critical the lap joint and butt joint methods may be untenable. If lap joint methods were used in such critical applications, such as the assembly of disk cartridges, small variations in component tolerances, such as bends and burrs in the metal components that occur during stamping, may be enough to cause tolerance problems in the finished disk cartridge. The dimensional tolerance problems would eventually prevent further technological advances that might be achieved due to further reductions in the size of disk cartridges. Moreover, to account for the component tolerance variations, the components themselves would have to meet extreme tolerances. As a result of the extreme component tolerances that would be necessary, the increased component cost would ultimately increase disk cartridge cost.
The extreme component tolerances and higher disk cartridge costs could be circumvented by an improved assembly process. Thus there is a need for an improved, economical assembly process of disk cartridges that insures consistency in the dimensional relationships among components.